Optical sensors have been developed for detecting oxygen and which utilize organic or organometallic luminescent species. Such sensors have been disclosed in U.S. Pat. Nos. 3,612,866; 4,321,057; 4,399,099; 4,557,900; and 4,476,870; Lubbers, D. W. and Optiz, N., Sensors and Actuators, 4, 641-654, (1983); Lubbers, D. W., et al., IEEE Transactions on Biomedical Engineering, BME-33, 117-132, (1986); Fitzgerald, R. V. and Peterson, J. I., Anal. Chem., 56, 62-67, (1984); Wolfbeis, D. S., et al., Mikrochimica Acta, 153-158, (1984); and Hirschfeld, T.; Miller, H.; and Miller, F, Optrodes For In Vivo Real Time Monitoring of pCO.sub.2 and pO.sub.2, presented at the Pittsburgh Conference, Atlantic City, N.J., Mar. 1986.
While effective, these and other luminescence sensors have the disadvantage of being relatively insensitive to relatively small but significant changes in the concentration or the partial pressure of oxygen in media. Another disadvantage is that the dynamic range over which oxygen can be measured by such sensors is limited, due to their non-linear response at higher oxygen concentrations. And still yet another disadvantage of known sensors is their use in medical applications, where gaseous or volatile anesthetics, such as halothane (bromochlorotrifluoroethane) are employed. These anesthetics will interfere with a luminescence sensor in measuring, for example, oxygen in the blood. The interference by the anesthetic will render such sensors unusable, particularly during critical surgical operations. It would be desirable to obtain a sensor and a method for measuring oxygen concentrations that are more sensitive, have a wider dynamic (i.e. linear) range for measuring oxygen, and are more resistant to interference by anesthetics than are known sensors for measuring oxygen concentrations or partial pressures.